Basically she's saying
Shes tried being with other people, but nothing compares to her first love, which is this guy!
The fact is though , deep down she knows she and this guy will never be together and her dreams will never come true. For reasons such as unrequited love, or other reasons. So she know's she can't let go , nothing or nobody else compares to this guy. So she's saying well If I can't have you then sod it I'll remain single, I don't want nobody else.
Basically she's saying Shes tried being with other people, but nothing compares to her first love, which is this guy! The fact is though , deep down she knows she and this guy will never be together and her dreams will never come true. For reasons such as unrequited love, or other reasons. So she know's she can't let go , nothing or nobody else compares to this guy. So she's saying well If I can't have you then sod it I'll remain single, I don't want nobody else.